Measuring equipment for use in connection with hip prosthesis surgery

Abstract

A measuring adapter for a measuring instrument for use in connection with hip prosthesis surgery comprises a measuring head and a connector. The measuring head comprises a front end, a rear end and convex upper surface and is divided into at least two separate sections. The measuring head comprises an axially extending central through-going bore adapted to receive an actuating rod. The measuring head is expandable from a relaxed state to an expanded state by axially displacing the actuating rod in the central through-going bore. The connector is hollow and divided at one end in axial direction of the measuring head into a number of legs corresponding to the number of separate sections of the measuring head; each leg being connected to one of the sections of the measuring head. At least a part of the upper surface of the measuring head is adapted, when in the expanded state, to adopt the shape of a spherical cap or a convex shape comprising at least a spherical segment.

The invention claimed is: 
     
       1. A measuring adapter for a measuring instrument for use in connection with hip prosthesis surgery, wherein the measuring adapter comprises:
 a measuring head comprising a front end, a rear end and an upper surface; the measuring head being divided into at least two separate sections; and 
 a connector; the connector being hollow and slotted at one end in an axial direction of the measuring head into a number of legs, the number of legs corresponding to the number of the at least two separate sections of the measuring head; wherein each leg of the connector is connected to one of the at least two separate sections of the measuring head on the rear end of the measuring head; 
 wherein at least a part of the upper surface of the measuring head is adapted to be moved from a relaxed state to an expanded state, 
 wherein in the expanded state the at least a part of upper surface of the measuring head defines an expanded-state perimeter and the at least a part of the upper surface of the measuring head adopts the shape of
 a spherical cap; or 
 a convex shape comprising at least a spherical segment, and 
 
 wherein, in the relaxed state, the at least a part of the upper surface of the measuring head is within the expanded-state perimeter. 
 
     
     
       2. A measuring adapter according to  claim 1 , wherein the measuring adapter comprises a bore adapted to receive an actuating rod, wherein the measuring head is adapted to expand from the relaxed state to the expanded state when the actuating rod is displaced in the bore. 
     
     
       3. A measuring adapter according to  claim 2 , wherein the measuring adapter is connected to a measuring arrangement which is adapted to measure the relative displacement of the actuation rod in relation to a fixed point in the measuring adapter. 
     
     
       4. A measuring adapter according to  claim 1 , wherein the actuating rod is connected to a computer, and wherein the computer is adapted to control the relative displacement of the actuation rod relative to the measuring head. 
     
     
       5. A measuring adapter according to  claim 1 , wherein the adapter is connected to a pressure registering unit configured to measure the pressure exerted by the measuring head. 
     
     
       6. A measuring adapter according to  claim 5 , wherein the pressure registering unit comprises piezo-electric crystals. 
     
     
       7. A measuring adapter according to  claim 5 , wherein the pressure registering unit is configured to transmit pressure measurements to a computer. 
     
     
       8. The measuring adapter according to  claim 1 , wherein the measuring head comprises windows, the windows being sized and positioned to allow a user to observe the position of the segments of the measuring head relative to a milled acetabulum in order to observe the size of a milled cavity of the acetabulum. 
     
     
       9. The measuring adapter according to  claim 1 , wherein the measuring head is divided into at least three separate sections. 
     
     
       10. The measuring adapter according to  claim 1 , wherein the at least a part of the upper surface of the measuring head comprises a rough surface. 
     
     
       11. The measuring adapter according to  claim 1 , wherein the upper surface of the measuring head of the measuring adapter comprises a rough surface at a lower part of the upper surface and a smooth surface on an upper part of the upper surface. 
     
     
       12. The measuring adapter according to  claim 1 , wherein the connector comprises a securing arrangement provided at an opposite end of the connector relative to a connection to the measuring head. 
     
     
       13. The measuring adapter according to  claim 12 , wherein the securing arrangement comprises at least one recess for a bayonet socket. 
     
     
       14. The measuring adapter according to  claim 1 , wherein the measuring adapter is made of a hard yet flexible material, wherein the material is chosen from the group consisting of a metal alloy, a plastic material, a plastic composite, a ceramic material and combinations thereof. 
     
     
       15. A measuring instrument comprising
 a measuring adapter according to  claim 1  and 
 a measuring unit comprising:
 an actuating rod adapted to be received by a bore of the measuring adapter, wherein a main part of the actuating rod is adapted to interact displaceably with the bore of the measuring adapter and thereby change the diameter of the measuring head, and 
 a handle means, wherein in connection with the handle means, means for displacement of the actuation rod and registration of the relative displacement of the actuation rod relative to the measuring head is provided. 
 
 
     
     
       16. A measuring adapter for a measuring instrument for use in connection with hip prosthesis surgery, wherein
 the measuring adapter comprises a measuring head and a connector; 
 the measuring head comprises a front end, a rear end and an upper surface; wherein
 the upper surface is convex; 
 the measuring head is adapted to expand from a relaxed state to an expanded state; and 
 the measuring head is divided into at least two separate sections; 
 
 the connector is hollow and slotted at one end in an axial direction of the measuring head to define a number of legs, the number of legs corresponding to the number of the at least two separate sections of the measuring head; wherein
 the legs of the connector are each connected to one of the at least two separate sections of the measuring head on the rear end of the measuring head; and 
 
 the measuring head comprises windows, the windows being sized and positioned to allow a user to observe the position of the segments of the measuring head relative to a milled acetabulum in order to observe the size of a milled cavity of the acetabulum. 
 
     
     
       17. A measuring instrument comprising
 a measuring adapter according to  claim 16  and 
 a measuring unit comprising
 an actuating rod adapted to be received by a bore of the measuring adapter, wherein a main part of the actuating rod is adapted to interact displaceably with the bore of the measuring adapter and thereby change the diameter of the measuring head, and 
 a handle means, wherein in connection with the handle means, means for displacement of the actuation rod and registration of the relative displacement of the actuation rod relative to the measuring head is provided.